Five days versus one day of penicillin as prophylaxis in elective neurosurgical operations

Of 423 patients undergoing elective cranial and spinal operations, infections due to Staphylococcus aureus occurred in 3 of 217 (1.4%) receiving penicillin for 1 day, in none of 206 receiving penicillin for 5 days. There was no significant difference in rates of infection between the two groups receiving penicillin. It is concluded that penicillin for 1 day is as effective as penicillin for 5 days, in the prevention of wound infections due to S. aureus.     

Impact of treating Staphylococcus aureus nasal carriers on wound infections in cardiac surgery

Staphylococcus aureus is a common cause of postoperative wound infections, and nasal colonization by this organism is an important factor in the development of infections. Treatment with mupirocin can eradicate the organism in the short term, and prophylactic treatment of colonized patients may prevent postoperative S. aureus infections. A double-blind, randomized, placebo-controlled trial was performed to determine whether nasal mupirocin administered pre-operatively to S. aureus carriers reduces the rates of sternal and leg wound infections after cardiac surgery. The study enrolled 263 patients with nasal S. aureus undergoing elective cardiac surgery at St. Michael's Hospital, Toronto, Canada. Patients were assessed for infections in the immediate postoperative period and two months later. Two hundred and fifty-seven patients were included in the intention-to-treat analysis and re-analysed according to the actual treatment applied. Wound infections occurred in 17 (13.5%) mupirocin recipients and 11 (9.1%) placebo recipients (P=0.319), with seven (5.4%) and six (4.7%) sternal infections, respectively. Two (1.6%) wound infections were acquired postoperatively in the mupirocin group, neither of which were caused by S. aureus. The placebo group had three (2.4%) nosocomial wound infections, with two (1.6%) S. aureus bacteraemias (P=0.243). Among patients receiving mupirocin, 106 (81.5%) cleared S. aureus compared with 59 (46.5%) patients receiving placebo (P<0.0001). There was no significant difference between intention-to-treat and actual treatment groups. Prophylactic intranasal mupirocin administered to S. aureus carriers did not reduce the rates of overall surgical site infections by S. aureus, and only showed a trend towards decreased incidence of nosocomial S. aureus infections.     

Drug susceptibility of staphylococci isolated from clinical specimens

Eighty-eight strains of staphylococci were isolated from a variety of specimens collected from patients at our university hospital from June to August 1982. These strains were identified as Staphylococcus aureus (86%), Staphylococcus epidermidis (6.8%), Staphylococcus haemolyticus (2.3%), Staphylococcus capitis (2.3%), and Staphylococcus simulans (1.1%). One strain could not be identified with certainty as a currently recognized species. A majority (70%) of the S. aureus strains was resistant to two or more of the following drugs; penicillin G, kanamycin, doxycycline, erythromycin, and chloramphenicol. As for susceptibility to beta-lactam antibiotics, most of the strains that were resistant to penicillin G were also resistant to aminobenzyl penicillin and cephalexin. Whereas none of the strains was resistant to methicillin, cloxacillin, dicloxacillin, nor cefmetazole, and only a few strains were resistant to cefoperazone or cefazolin or both. Over 50% of the S. aureus strains were found to be resistant to each of four aminoglycosides (Kanamycin, gentamicin, tobramycin, and sagamicin), while only 5% of the strains were resistant to amikacin. Multiple resistance to the above four aminoglycosides was observed among more than 40% of the S. aureus strains, and also observed among three of six strains of S. epidermidis.     

Use of perioperative mupirocin to prevent methicillin-resistant Staphylococcus aureus (MRSA) orthopaedic surgical site infections

We have examined whether topical perioperative prophylaxis can reduce the incidence of methicillin-resistant Staphylococcus aureus (MRSA) surgical site infections (SSIs). Using a controlled before and after approach on patients from four orthopaedic wards, undergoing orthopaedic surgery involving insertion of metal prostheses and/or fixation, received perioperative prophylaxis with nasal mupirocin for five days, and a shower or bath with 2% (v/v) triclosan before surgery (PPNMT). After introduction of PPNMT there was a marked decrease in incidence of MRSA SSIs (per 1000 operations) from 23 in the six months beforehand (period A) to 3.3 (P<0.001) and 4 (P<0.001) in subsequent consecutive six-month periods (B and C, respectively). Of 11 MRSA SSI cases that occurred during periods B and C, only one had actually received PPNMT, and 10 occurred after acute, as opposed to elective, surgery (P<0.001). Point prevalence nasal MRSA carriage decreased from 38% before PPNMT to 23% immediately after, and 20%, 7%, 10% and 8% (P<0.001) at six-monthly intervals post-intervention. Conversely, the prevalence of nasal MRSA carriage in a control elderly medicine ward did not change significantly. Vancomycin usage, in terms of defined daily doses, declined by 23%. Low-level mupirocin resistance was found in 2.3% of S. aureus isolates from orthopaedic patients before PPNMT, and in 3.9%, 6.1%, 10% and 0% in subsequent six month periods. No S. aureus isolates with high-level mupirocin resistance were found. PPNMT can reduce the incidence of MRSA SSls after orthopaedic surgery, probably by reducing nasal MRSA carriage in the endemic setting, without selecting for mupirocin resistance.     

An outbreak of infection due to Staphylococcus aureus phage type 52 in a neonatal intensive care unit.

An outbreak of infection due to Staphylococcus aureus phage-type 52, resistant only to penicillin, occurred in children's wards primarily in a neonatal intensive care unit. The outbreak involved 86 infants; the majority presented with conjunctivitis, wound infections, boils, omphalitis and otitis externa. Seven per cent of these infants (six of 86) also had septicaemia. In addition, 6% (five of 86) were colonized by this phage type and the most common site of carriage was the umbilicus. The outbreak was contained by eradication of nasal carriage among the staff members and also by standard infection control measures.     

Timing and aetiology of bacterial infections in a liver intensive care unit

We undertook a prospective study of 887 consecutive adult patients admitted over an 11 year period to a liver intensive care unit. One or more bacterial infections occurred in 335 (37.8%) patients. Gram-positive cocci predominated. In relation to the date of admission these infections occurred in a statistically significant sequence. Streptococci infections were earliest (median time to infection two days), followed by Staphylococcus aureus (three days), coagulase-negative staphylococci (six days) and enterococci (eight days). Escherichia coli infections occurred earlier than those due to klebsiella-enterobacter (two vs seven days; P = 0.0001) and, overall, Enterobacteriaceae earlier than non-fermentative Gram-negatives (four vs. eight days; P = 0.0081). This study contributes to the management of high-dependency patients by confirming statistically the timing and sequence of infecting bacteria in patients with acute liver failure.     

呼吸机相关性肺炎病原菌分布及其耐药性分析

目的明确呼吸机相关性肺炎(VAP)病原菌的流行分布及耐药特点。方法对气管切开并实施机械通气>48 h的261例患者下呼吸道分泌物,进行细菌定量培养及抗菌药物敏感性测定。结果从气管切开至发生VAP的时间为3~126 d,平均18.2 d;发生VAP 92例,发生率为35.2%,死亡率为35.9%;92例VAP患者下呼吸道分泌物培养出病原菌276株,病原菌种分布:革兰阴性杆菌170株,占61.6%,主要为假单胞菌属、不动杆菌属、克雷伯菌属、肠杆菌属;革兰阳性球菌57株,占20.6%,主要为金黄色葡萄球菌、表皮葡萄球菌、肠球菌属,真菌感染占17.8%,主要为假丝酵母菌属;各类病原菌混合感染者88.0%,主要病原菌药敏试验结果,革兰阴性杆菌对亚胺培南总敏感性最高,其次为头孢哌酮/舒巴坦、阿米卡星、环丙沙星、替卡西林/克拉维酸、头孢他啶,对氨苄西林、第二代头孢菌素、头孢噻肟、头孢曲松则有较高的耐药性;金黄色葡萄球菌耐药现象严重,对青霉素、苯唑西林的耐药率分别达100.0%、91.3%,但对万古霉素、替考拉宁尚敏感。结论VAP的主要病原菌为革兰阴性杆菌且存在较严重的耐药现象,混合感染现象严重,应引起临床高度重视。     

Randomized clinical trial of intra-operative antimicrobial prophylaxis of infection after neurosurgical procedures

A randomized, placebo-controlled, double-blind and sequentially analysed clinical trial to determine the efficacy of intra-operative parenteral gentamicin and vancomycin (with streptomycin in the irrigating solution) in preventing infection at the operative site following neurosurgical procedures is described. Patients receiving prophylaxis had a significantly (P = 0.046) lower operative site infection rate (2/71 = 2.8%) than those receiving placebo (9/77 = 11.7%). This difference was most apparent during an epidemic, the source of which was not evident. Moreover, a total of 13 infections (two operative site, five pneumonia and six urinary tract) occurred among 12 patients receiving prophylaxis, whereas there was a total of 31 infections (nine operative site, nine pneumonia, 10 urinary tract and three septicaemia) among 24 patients receiving placebo. A smaller quantity of antimicrobial drugs was administered postoperatively to patients receiving prophylaxis (3.96 'antibiotic-days' per patient) than to those receiving placebo (6.87 'antibiotic-days' per patient).     

Outcome following haemodialysis catheter-related Staphylococcus aureus bacteraemia

Staphylococcus aureus is a frequent cause of haemodialysis access-related bacteraemia. The propensity for this organism to seed from the bloodstream to distant sites is well recognized, but the rate at which this occurs is poorly defined in patients with removable haemodialysis catheters. This retrospective study identified 47 patients with 50 episodes of S. aureus haemodialysis catheter-related bacteraemia between August 1993 and December 1995. Adverse events were recorded until February 1996. Thirty of 50 episodes (60%) were apparently uncomplicated. Bacterial seeding to heart valves or distant sites was documented in eight episodes (16%), of which six occurred during antibiotic therapy. A further 12 patients had persistent bacteraemia in the absence of a defined focus of infection, the last positive blood culture ranging from 2-19 days (mean 6.6, median 5) after removal of the haemodialysis catheter and commencing appropriate antibiotic treatment. The serious nature of this infection confirms the need for prevention, together with effective strategies for investigation and treatment in this patient population.     

Methicillin resistance and risk factors for embolism in Staphylococcus aureus infective endocarditis.

OBJECTIVE: Infective endocarditis caused by Staphylococcus aureus is an ominous prognosis associated with a high prevalence of embolic episodes and neurological involvement. Whether methicillin resistance decreases the risk of embolism in infective endocarditis is unclear. We sought to assess the association between methicillin resistance and risk factors for embolism in S. aureus infective endocarditis. DESIGN: Retrospective chart review. Data from patients with infective endocarditis due to methicillin-resistant S. aureus were compared with data from patients with endocarditis due to methicillin-susceptible S. aureus. Logistic regression was used to identify independent risk factors for embolism. SETTING: A 2,000-bed, university-affiliated tertiary care hospital. PATIENTS: Between 1995 and 2005, 123 patients with S. aureus infective endocarditis were included in the study. There were 74 male patients and 49 female patients, with a median age of 54 years (range, 0-89 years). RESULTS: Of 123 infections, 30 (24%) were nosocomial infections, and 14 (11%) were prosthetic valve infections. Of 123 S. aureus isolates, 48 (39%) were methicillin resistant. In total, embolism occurred in 45 (37%) of these patients: pulmonary embolism in 22 (18%), cerebral embolism in 21 (17%), and peripheral embolism in 6 (5%). The independent risk factors for an embolism were injection drug use, presence of a cardiac vegetation with a size of 10 mm or greater, and absence of nosocomial infection. For 83 patients with aortic or mitral infective endocarditis, independent risk factors for an embolism were the presence of a cardiac vegetation with a size of 10 mm or greater and endocarditis due to methicillin-susceptible S. aureus. Overall, in-hospital death occurred for 32 (26%) of 123 patients. Methicillin-resistant infection was not an independent risk factor for death. CONCLUSIONS: Methicillin-resistant S. aureus infection was associated with decreased risk of embolism in left-side endocarditis, but was not associated with in-hospital death.     

急诊科预防清创缝合术后感染护理干预探讨

目的 探讨护理干预对急诊科预防清创缝合术后感染的临床效果,为预防感染发生提供参考资料.方法 选取医院急诊科清创缝合并给与护理干预患者196例为观察组,选取同期急诊科清创缝合未给予护理干预患者140例为对照组,将两组患者术后感染及细菌培养结果进行统计分析.结果 清创缝合术后7d,观察组感染9例,感染率4.59％,对照组感染16例,感染率11.43％,两组差异有统计学意义(P＜0.05);经细菌培养,观察组感染主要为金黄色葡萄球菌,占33.33％,表皮葡萄球菌占22.22％,对照组感染主要为金黄色葡萄球菌,占25.00％,表皮葡萄球菌占18.75％,溶血葡萄球菌占18.75％.结论 通过护理干预模式,能有效降低清创缝合术后患者的感染率,改善患者的伤口愈合,提高临床治疗效果.     

Efficacy of mupirocin nasal ointment in eradicating Staphylococcus aureus nasal carriage in chronic haemodialysis patients.

Topical 2% mupirocin ointment eradicated chronic Staphylococcus aureus nasal carriage immediately post-therapy in 17 (77%) of 22 haemodialysis patients. Mean time to recurrence was 3.8 weeks. Similar pre-therapy and post-therapy phage types occurred in 12 (71%) of 17 patients. Staphylococcus aureus infections developed in none of 17 successfully treated patients, two of five treatment failures (P = 0.05), and 10 of 46 untreated patients studied concurrently (P = 0.03).     

金黄色葡萄球菌耐药的现状及临床治疗对策

目的分析医院与社区获得性感染的金黄色葡萄球菌(SAU)耐药现状,给临床合理用药提供参考。方法收集2004-2006年临床分离的金黄色葡萄球菌,培养鉴定,采用纸片扩散法(K-B法)或微量稀释法(MIC)测定16种抗菌药物的敏感情况,用WHONET5软件进行分析。结果440株金黄色葡萄球菌,其中耐甲氧西林金黄色葡萄球菌(MRSA)为260株,占59.1%;甲氧西林敏感金黄色葡萄球菌(MSSA)为180株,占40.9%;SAU对16种抗菌药物的耐药率最高的是青霉素G为85.5%、万古霉素耐药率为0。结论MSSA对大部分抗菌药物仍保持较好的敏感性,而MRSA表现为多重耐药性,但万古霉素例外,所以对耐万古霉素金黄色葡萄球菌(VISA及VRSA)的连续监测、了解葡萄球菌属的耐药机制具有重要的临床意义。     

Effect of vancomycin therapy for osteomyelitis on colonization by methicillin-resistant Staphylococcus aureus: lack of emergence of glycopeptide resistance.

BACKGROUND: In treating orthopedic infections, the long-term impact of vancomycin therapy on colonization by methicillin-resistant Staphylococcus aureus (MRSA) and the emergence of vancomycin-intermediate S. aureus is unknown. DESIGN: Prospective surveillance of the effect of long-term vancomycin therapy on colonization by MRSA and the emergence of vancomycin-intermediate S. aureus. METHODS: Thirty-four patients with MRSA osteomyelitis that was microbiologically documented were longitudinally observed for the emergence of vancomycin-intermediate S. aureus at 3 body sites (wound, anterior nares, and groin) during the initial period of vancomycin therapy and at the 2-month follow-up. Twenty patients received the standard dose (20 mg/kg/d) for 34 +/- 6 days and 14 patients received a high dose (40 mg/kg/d) of vancomycin for 37 +/- 9 days. RESULTS: During vancomycin treatment, global MRSA carriage (all body sites) fell from 100% to 25% in the group of patients receiving the standard dose of vancomycin, and from 100% to 40% in the group receiving the high dose. During the 2-month follow-up period after vancomycin therapy, global MRSA carriage increased from 25% to 55% in the group receiving the standard dose and decreased from 43% to 36% in the group receiving the high dose. CONCLUSION: Therapy with a high dose of vancomycin contributes to the sustained eradication of MRSA carriage without promoting the emergence of glycopeptide resistance.     

Staphylococcus aureus bacteremia in older adults: predictors of 7-day mortality and infection with a methicillin-resistant strain.

OBJECTIVES: To determine the predictors of 7-day mortality in older adult patients with Staphylococcus aureus bacteremia after controlling for comorbidity using the Charlson weighted index of comorbidity (WIC) and to identify the risk factors associated with bacteremia due to methicillin-resistant S. aureus (MRSA). DESIGN. Retrospective cohort study from January 2003 until December 2004. SETTING. Two tertiary care, university-affiliated hospitals. METHODS. One hundred thirty-five hospitalized patients with S. aureus bacteremia were included in the study. All patients who were 60 years or older and had 1 or more blood cultures positive for S. aureus were included in the study. The primary outcome was death 7 days after the onset of S. aureus bacteremia. RESULTS. Twenty-one patients (15.6%) died within 7 days after the onset of S. aureus bacteremia. Seventy-four patients (56.1%) had MRSA bacteremia. Multivariate analysis identified 3 independent determinants of 7-day mortality: Charlson WIC score greater than 5 (odds ratio [OR], 3.6 [95% confidence interval {CI}, 1.1-11.2]; P=.03), previous hospitalization in the past 3 months (OR, 5.0 [95% CI, 1.1-25.1]; P=.04), and altered mental status at the onset of S. aureus bacteremia (OR, 13.6 [95% CI, 2.9-64.6]; P=.001). Multivariate analysis identified previous hospitalization in the past 3 months (OR, 2.6 [95% CI, 1.1-5.9]; P=.02), residence in a long-term care facility (OR, 4.5 [95% CI, 1.7-12.3]; P=.003), and altered mental status at the onset of S. aureus bacteremia (OR, 2.5 [95% CI, 1.5-5.6]; P=.02) to be independently associated with the presence of MRSA. CONCLUSIONS: The Charlson WIC is significantly associated with increased mortality of S. aureus bacteremia in older adults. Previous hospitalization in the past 3 months, residence in a long-term care facility, and altered mental status should be used as a guidance for empirical vancomycin therapy and application of infection control measures in older adults with suspected S. aureus bacteremia.     

Evolution of Staphylococcus aureus resistance to erythromycin in Denmark, 1959 to 1988: correlations between characteristics of erythromycin-resistant bacteraemia strains.

In an attempt to characterize erythromycin-resistant Staphylococcus aureus we present the intricate relationships between the following factors: phage type, period of isolation, antibiogram, minimum inhibitory concentration (MIC) to erythromycin, inducible or constitutive resistance, spectinomycin susceptibility, hospital- or community-acquired infection, and mortality rate. We studied 718 cases of bacteraemia with erythromycin-resistant S. aureus, occurring between 1959 and 1988. Central factors were phage type pattern, period of isolation, and antibiogram. Between 1959 and 1973 the majority of the erythromycin-resistant strains were multiresistant and belonged to the 83A complex and the related group III. They were mainly inducibly resistant, spectinomycin resistant, and had intermediate MICs (1-4 mg l-1) to erythromycin. The majority of these strains came from hospital-acquired infections and still exist today, although in decreased numbers. By contrast, erythromycin-resistant S. aureus isolated in recent years are usually co-resistant only to penicillin and more rarely also to tetracycline. These strains have inducible resistance, are spectinomycin susceptible, and have a high erythromycin MIC. They are isolated both from hospital- and community-acquired infections. Strains with constitutive resistance to macrolides occurred at a stable low level (13%) during the whole observation period and always had high MICs to erythromycin. The mortality rate among patients with S. aureus bacteraemia due to an erythromycin-resistant strain was only associated with the year of infection and decreased from 61% in the first 15-year period to 40% in the subsequent 15 years.     

Susceptibility patterns of Staphylococcus in a family practice population.

Nasal swabs were obtained from 408 patients seen in a family practice office in an attempt to identify Staphylococcus aureus carriers. Isolated strains were tested for sensitivity to 11 antibiotics. Study participants were interviewed to obtain the following data: age, history of recent hospitalization and/or recent antibiotic use, number of household members, and occupation, if employed in a health-care facility. S aureus was isolated from 109 nasal swabs. This represents a 26.7 percent carrier rate. Only 25.7 percent of the isolates were sensitive to penicillin G and ampicillin. No statistically significant association was found between the patient variables and either the carrier rate or the sensitivity of the S aureus isolates to penicillin. The sensitivity testing demonstrated that 94.5 percent of the isolates were sensitive to tetracycline and erythromycin. Ninety-nine to 100 percent of the isolates were sensitive to all other antibiotics tested. The authors conclude that penicillin G should not be used in the treatment of S aureus infections. Erythromycin, due to demonstrated sensitivity and reasonable cost, is recommended for mild to moderate infections.     

Septicaemia as a hospital hazard

In 1 year there were 135 episodes of septicaemia in a large referral hospital serving a population of 400,000 people. Of these, 52 were hospital-acquired giving a nosocomial septicaemia rate of 2.08 per 1000 admissions. The mortality rate rose with the number of antibiotics used; from 15% in those receiving one drug to 50% in those receiving three. A wide variety of organisms were encountered, the largest group being Staphylococcus aureus, 12 episodes; and Escherichia coli, nine episodes. Staphylococcus epidermis was pathogenic in seven patients with one death. A review of possible aetiological factors showed that 28 episodes occurred postoperatively with surgery considered directly responsible in 20. Intravenous cannulae were in place in 39 patients at the time of development of infection; they were causal in at least five; with two deaths. Urinary catheters were in situ in 14 patients and causal in at least six, with two deaths. Immunosuppression by drugs carried a worse prognosis than when infection occurred in patients with immunosuppressive disease.     

Antimicrobial resistance profile of Staphylococcus aureus isolated from clinical samples and foods of animal origin

Staphylococcus aureus has been well established as a clinical and epidemiological pathogen and can cause infections at many anatomical sites. Increasing insusceptibility to β-lactams and the glycopeptides complicates the treatment of these infections. We isolated 584 strains of S. aureus from various clinical and animal origin food samples during (from January 2006 to December 2007) the survey. Resistance to 15 antibiotics frequently used in human medicine and veterinary practice was also determined. A remarkable level of penicillin resistance was detected in both clinical (98.3%) and food (92.0%) S. aureus isolates. But, there were no S. aureus strains that were resistant to vancomycin, teicoplanin, linezolid, and quinupristin/dalfobristin. The rate of resistance to tetracycline, ciprofloxacin, levofloxacin, methicillin, gentamicin, tobramycin, norfloxacin, and moxifloxacin among the human and foods S. aureus isolates ranged from 50.3% to 56.3% and 1.4% to 9.5%, respectively. In our survey, in vitro susceptibility data suggested that the incidence of resistance among the S. aureus strains isolated from food were not remarkably high, excluding penicillin. Although the transfer of antibiotic resistance of S. aureus from foods to humans probably occurs less frequently than is generally assumed, the increasing prevalence of resistance in the strains of human origin may have important therapeutic implications.